staging: fsl-dpaa2/eth: Refactor fq taildrop setup

With the introduction of PFC support, there are multiple ways taildrop
is configured, based on the DPNI pause frame configuration:
- no pause frames - per-queue taildrop thresholds.
- pause frames - no taildrop thresholds (pause frames sent based on
  buffer depletion).
- PFC pause frames - per-group (traffic class) taildrop thresholds for
  non-PFC enabled priorities (pause frames sent based on Rx congestion
  notifications).

Refactor the fq taildrop setup area.

Signed-off-by: Bogdan Purcareata <bogdan.purcareata@nxp.com>

3 files changed, 119 insertions, 21 deletions

diff --git a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c
index e4844ae..5523e58 100644
--- a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c
+++ b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c
@@ -2116,7 +2116,7 @@ static int setup_dpni(struct fsl_mc_device *ls_dev)
 
 	/* Enable flow control */
 	cfg.options = DPNI_LINK_OPT_AUTONEG | DPNI_LINK_OPT_PAUSE;
-	priv->tx_pause_frames = 1;
+	priv->tx_pause_frames = true;
 
 	err = dpni_set_link_cfg(priv->mc_io, 0, priv->mc_token, &cfg);
 	if (err) {
@@ -2158,24 +2158,12 @@ static void free_dpni(struct dpaa2_eth_priv *priv)
 	kfree(priv->cscn_unaligned);
 }
 
-int setup_fqs_taildrop(struct dpaa2_eth_priv *priv,
-		       bool enable)
+static int set_queue_taildrop(struct dpaa2_eth_priv *priv,
+			      struct dpni_taildrop *td)
 {
 	struct device *dev = priv->net_dev->dev.parent;
-	struct dpni_taildrop td;
-	int err = 0, i;
-
-	td.enable = enable;
-	td.threshold = DPAA2_ETH_TAILDROP_THRESH;
+	int err, i;
 
-	if (enable) {
-		priv->num_bufs = DPAA2_ETH_NUM_BUFS_TD;
-		priv->refill_thresh = DPAA2_ETH_REFILL_THRESH_TD;
-	} else {
-		priv->num_bufs = DPAA2_ETH_NUM_BUFS_FC /
-			priv->num_channels;
-		priv->refill_thresh = priv->num_bufs - DPAA2_ETH_BUFS_PER_CMD;
-	}
 
 	for (i = 0; i < priv->num_fqs; i++) {
 		if (priv->fq[i].type != DPAA2_RX_FQ)
@@ -2184,14 +2172,97 @@ int setup_fqs_taildrop(struct dpaa2_eth_priv *priv,
 		err = dpni_set_taildrop(priv->mc_io, 0, priv->mc_token,
 					DPNI_CP_QUEUE, DPNI_QUEUE_RX,
 					priv->fq[i].tc, priv->fq[i].flowid,
-					&td);
+					td);
 		if (err) {
 			dev_err(dev, "dpni_set_taildrop() failed (%d)\n", err);
-			break;
+			return err;
 		}
 	}
 
-	return err;
+	return 0;
+}
+
+static int set_group_taildrop(struct dpaa2_eth_priv *priv,
+			      struct dpni_taildrop *td)
+{
+	struct device *dev = priv->net_dev->dev.parent;
+	struct dpni_taildrop disable_td, *tc_td;
+	int i, err;
+
+	memset(&disable_td, 0, sizeof(struct dpni_taildrop));
+	for (i = 0; i < dpaa2_eth_tc_count(priv); i++) {
+		if (td->enable && dpaa2_eth_is_pfc_enabled(priv, i))
+			/* Do not set taildrop thresholds for PFC-enabled
+			 * traffic classes. We will enable congestion
+			 * notifications for them.
+			 */
+			tc_td = &disable_td;
+		else
+			tc_td = td;
+
+		err = dpni_set_taildrop(priv->mc_io, 0, priv->mc_token,
+					DPNI_CP_GROUP, DPNI_QUEUE_RX,
+					i, 0, tc_td);
+		if (err) {
+			dev_err(dev, "dpni_set_taildrop() failed (%d)\n", err);
+			return err;
+		}
+	}
+	return 0;
+}
+
+/* Enable/disable Rx FQ taildrop
+ *
+ * Rx FQ taildrop is mutually exclusive with flow control and it only gets
+ * disabled when FC is active. Depending on FC status, we need to compute
+ * the maximum number of buffers in the pool differently, so use the
+ * opportunity to update max number of buffers as well.
+ */
+int set_rx_taildrop(struct dpaa2_eth_priv *priv)
+{
+	enum dpaa2_eth_td_cfg cfg = dpaa2_eth_get_td_type(priv);
+	struct dpni_taildrop td_queue, td_group;
+	int err = 0;
+
+	switch (cfg) {
+	case DPAA2_ETH_TD_NONE:
+		memset(&td_queue, 0, sizeof(struct dpni_taildrop));
+		memset(&td_group, 0, sizeof(struct dpni_taildrop));
+		priv->max_bufs_per_ch = DPAA2_ETH_NUM_BUFS_FC /
+					priv->num_channels;
+		break;
+	case DPAA2_ETH_TD_QUEUE:
+		memset(&td_group, 0, sizeof(struct dpni_taildrop));
+		td_queue.enable = 1;
+		td_queue.units = DPNI_CONGESTION_UNIT_BYTES;
+		td_queue.threshold = DPAA2_ETH_TAILDROP_THRESH /
+				     dpaa2_eth_tc_count(priv);
+		priv->max_bufs_per_ch = DPAA2_ETH_NUM_BUFS_PER_CH;
+		break;
+	case DPAA2_ETH_TD_GROUP:
+		memset(&td_queue, 0, sizeof(struct dpni_taildrop));
+		td_group.enable = 1;
+		td_group.units = DPNI_CONGESTION_UNIT_FRAMES;
+		td_group.threshold = NAPI_POLL_WEIGHT *
+				     dpaa2_eth_queue_count(priv);
+		priv->max_bufs_per_ch = NAPI_POLL_WEIGHT *
+					dpaa2_eth_tc_count(priv);
+		break;
+	default:
+		break;
+	}
+
+	err = set_queue_taildrop(priv, &td_queue);
+	if (err)
+		return err;
+
+	err = set_group_taildrop(priv, &td_group);
+	if (err)
+		return err;
+
+	priv->refill_thresh = DPAA2_ETH_REFILL_THRESH(priv);
+
+	return 0;
 }
 
 static int setup_rx_flow(struct dpaa2_eth_priv *priv,
diff --git a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.h b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.h
index 4d2ac3a..3f5419d 100644
--- a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.h
+++ b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.h
@@ -436,6 +436,7 @@ struct dpaa2_eth_priv {
 	u8 dcbx_mode;
 	struct ieee_pfc pfc;
 	bool vlan_clsf_set;
+	bool tx_pause_frames;
 };
 
 #define dpaa2_eth_hash_enabled(priv)	\
@@ -466,7 +467,32 @@ static inline int dpaa2_eth_tc_count(struct dpaa2_eth_priv *priv)
 	return priv->dpni_attrs.num_tcs;
 }
 
+static inline bool dpaa2_eth_is_pfc_enabled(struct dpaa2_eth_priv *priv,
+					    int traffic_class)
+{
+	return priv->pfc.pfc_en & (1 << traffic_class);
+}
+
+enum dpaa2_eth_td_cfg {
+	DPAA2_ETH_TD_NONE,
+	DPAA2_ETH_TD_QUEUE,
+	DPAA2_ETH_TD_GROUP
+};
+
+static inline enum dpaa2_eth_td_cfg
+dpaa2_eth_get_td_type(struct dpaa2_eth_priv *priv)
+{
+	bool pfc_enabled = !!(priv->pfc.pfc_en);
+
+	if (pfc_enabled)
+		return DPAA2_ETH_TD_GROUP;
+	else if (priv->tx_pause_frames)
+		return DPAA2_ETH_TD_NONE;
+	else
+		return DPAA2_ETH_TD_QUEUE;
+}
+
 void check_cls_support(struct dpaa2_eth_priv *priv);
 
-int setup_fqs_taildrop(struct dpaa2_eth_priv *priv, bool enable);
+int set_rx_taildrop(struct dpaa2_eth_priv *priv);
 #endif	/* __DPAA2_H */
diff --git a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-ethtool.c b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-ethtool.c
index 4c2c654..304a21c 100644
--- a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-ethtool.c
+++ b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-ethtool.c
@@ -230,7 +230,8 @@ static int dpaa2_eth_set_pauseparam(struct net_device *net_dev,
 	if (current_tx_pause == pause->tx_pause)
 		goto out;
 
-	err = setup_fqs_taildrop(priv, !pause->tx_pause);
+	priv->tx_pause_frames = pause->tx_pause;
+	err = set_rx_taildrop(priv);
 	if (err)
 		netdev_dbg(net_dev, "ERROR %d configuring taildrop", err);